Plots often focus upon "unusual" events, things that are out of the ordinary which distinguish heroes from villains and so forth. In order to do this they must first establish the status quo, such as by using setting and tone and crafting an introduction. In Star Wars, for example, the status quo is Luke Skywalker working on his uncle's farm and dreaming of something more exciting. There isn't very much action going on here.

"Rising action" begins as soon as anything out of the ordinary starts to take place. Sometimes it's difficult to pin down precisely when this is; for example, in Lord of the Flies, the rising action (the war and the plane crash) take place before the book even begins. However, the beginning of the rising action is usually pretty clear; in Harry Potter, it's the arrival of Harry's acceptance letter to Hogwarts, in Fahrenheit 451, it's Montag's theft of a book, and in Beowulf, it's Grendel's attack on Heorot.

We should note that, despite the name, rising action does not mean that the action necessarily increases as time goes on, or that it's tied to a conflict, but this is often the case, and the point to which the action is rising is the climax of the story.

Rising action is characteristic of dramatic fiction and narrative fiction. It is an element of plot structure in literature. It guides the reader from the beginning of the story to its climax. The rising action encompasses the events of the story that take place before the climax. Falling action is what happens after the climax.

To help many in mapping out the elements of plot structure like rising action, a diagram is often drawn. The diagram is often of a pyramid. The rising action is on the left of the pyramid. At the top of the pyramid, one finds the climax. The right side of the pyramid is the falling action.

The rising action is a very important literary element that is basically required by all stories. The exact definition of rising action is:

The events of a dramatic or narrative plot that precede the climax

This means that it is basically the entire story leading up to the climax. If you think of a story as a mountain, the climax would be the peak, the rising action would be the side going up the mountain (you're "rising" up the mountain) and the other side would be the falling action (you're "falling" down the mountain).

The definition of rising action is all the events in a story that lead up to the greatest point of interest. Basically, it is all the information and events that lead up to the climax/turning point. The rising action foreshadows what the climax will be and gives you background information. The easiest example I can give you for this is Scooby Doo (lol). All the things that lead up to the monster chase is the rising action.